Many mesh tools involve selecting or manipulating nodes. Ensure that the nodes in the part are visible and selectable by activating the required layers in the Layers pane.
Use the 
Delete Entities command to remove from the mesh all entities that you select with the mouse cursor.
Tip: If you manually enter the entity to delete, you must also enter the entity ID. For example, if you want to delete node 400, enter N400 into the box and click Apply.
Note: Body faces or bodies of a CAD assembly cannot be deleted independently.